Diamond metal composite

ABSTRACT

The present invention relates to a method for producing diamond-metal composites including mixing diamond particles with metal-filler particles forming a diamond/metal-filler mixture, forming a green body of the diamond/metal-filler mixture, optionally green machining the green body to a work piece before or after pre-sintering by heating the green body to a temperature &lt;500° C., infiltrating the green body or the work piece with one or more wetting elements or infiltrating the green body or the work piece with one or more wetting alloys, which infiltration step being carried out under vacuum or in an inert gas atmosphere at a pressure &lt;200 Bar. The invention relates further to a green body, a diamond metal composite, and use of the diamond metal composite.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of co-pending U.S. patent application Ser. No. 12/741,318, entitled “Diamond Metal Composite,” and filed May 25, 2010, the subject matter of which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a method of manufacturing a diamond metal composite, a green body, a diamond metal composite, and uses of the diamond metal composite.

BACKGROUND

In many applications there are needs for materials having special properties, since the environment in which the materials are used could be abrasive, corrosive, erosive etc. Many of the materials used for the mentioned applications are manufactured under pressure and at high temperatures. Other materials are produced by complicated manufacturing methods, which include coating of particles. Some materials are produced by brazing.

One problem when producing a diamond composite is that diamonds are unreactive and do not easily form bonds to other elements. On the other hand, diamond is thermodynamically unstable at high temperature, and tends to convert to graphite. With increasing pressure, the stable area of diamond expands to higher temperature. This is a reason why most of the diamond composites existing today are made by process under high temperature and under high pressure. Another problem is high cost or the complicated manufacturing methods.

Yet another problem with the high-temperature- and high-pressure processes is that the process can only produce products having simple geometry, like discs or plates. Another problem with these processes is the size limitation, which means that it is not possible to produce products of larger size.

Another problem of a diamond composite is that diamond has low brazing ability. This limits the application of the composite, in which brazing of diamond is necessary on other material surface.

SUMMARY

The present invention solves at least the above-mentioned technical problems with a new method and the new material. Accordingly the present invention provides a new method for producing diamond metal composites, which method includes mixing diamond particles with metal-filler particles forming a diamond/metal-filler mixture, forming a green body of the diamond/metal-filler mixture, optionally green machining the green body to a work piece before or after pre-sintering by heating the green body to a temperature ≦500 ° C., infiltrating the green body or the work piece with one or more wetting elements or infiltrating the green body or the work piece with one or more wetting alloys, which infiltration step being carried out under vacuum or in an inert gas atmosphere at a pressure ≦200 Bar. Other embodiments of the invention are described in the Detailed Description and appended claims.

DETAILED DESCRIPTION

The above-described method of the invention gives the possibility to design the produced diamond composite and to produce a composite having the desired properties of a specific application. In general, with increasing content of the metal filler, the density, thermal expansion, fracture toughness and brazing ability will increase, but the hardness and Young's modulus decrease. The higher content of metal filler introduced into the materials, the wider range of the properties can be adjusted of the materials. Therefore, the method according to the invention comprises mixing metal filler particles (Me) in an amount less than 100 percent by weight (wt %) with diamond particles (D) in an amount D=100 wt %−Me forming a green body.

The filler particles are selected from one or more elements or one or more alloys of the elements from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), technetium (Tc), rhenium (Re), iron (Fe), cobalt (Co), nickel (Ni), and silicon (Si). According to one embodiment, the filler particles are selected from one or more elements or alloys of one or more elements of the group consisting of Ti, Cr, Mo, W and Co.

In one embodiment, the diamond-metal composite includes 0.1 to 55 wt % metal filler particles mixed with (e.g., combined with or added in any sequence) 45 to 99.9 wt % of diamond particles. In one embodiment, teight percent wt % is based upon the total weight of the metal-composite body. According to another embodiment the diamond-metal composite includes 0.5 to 50 wt % metal filler particles mixed with 50 to 99.5 wt % diamond particles. In another embodiment, the diamond-metal composite includes 0.1 to 45 wt % metal filler particles mixed with 55 to 99.9 wt % diamond particles. According to another embodiment the diamond metal composite includes 0.5 to 30 wt % metal filler particles mixed with 70 to 99.5 wt % diamond particles. According to another embodiment the diamond-metal composite includes 1.0 to 30 wt % metal filler particles mixed with 70 to 99 wt % diamond particles.

In one aspect, a method of making a diamond-metal composite includes mixing a diamond/filler mixture with a binder to stabilize the shape of the green body before pre-sintering. The binder could be any binder known in the art including but not limited to polymers, resin, cellulose, starch, and the like. The maximal amount of binder is less than 50% by volume for a porosity of less than 50 vol %. In principle, the amount of binder should be as small as possible if the formed green body is strong enough. The amount needed is dependent on what kind of binder is used, particle size and product design. According to one alternative of the invention the amount of binder may be ≦10 percent by weight (wt %). But in some cases, such as in powder injection moulding it may be ≦20 percent by weight (wt %) of binders. In one embodiment, Diamond powder with a particle size range 5-30 μm is mixed with Cr powder in different weight ratio. In the following green body is defined as the body formed of the diamond/filler mixture with or without addition of a binder, and work piece is defined as the product of the green machined green body. In one embodiment, the metal/diamond weight ratio is 90:10.

According to one embodiment, the method includes spray drying the diamond/filler/binder mixture into granules, and then forming the granules into a green body by pressing. According to another alternative the method may include forming the diamond/filler/binder mixture into a green body by one of the processes in the group consisting of casting, injection moulding, roll compaction, and extrusion.

A green machining of the green body before and/or after pre-sintering can be performed by traditional ways, such as cutting, sawing, drilling, milling, and turning etc. This step can effectively minimize or avoid the final machining on a hard body.

In the method according to the invention the pre-sintering is carried out at a temperature less or equal to 500° C. in the air, an inert gas atmosphere or in vacuum. According to one alternative of the invention the pre-sintering temperature may be less than or equal to 450° C. According to one alternative of the invention the pre-sintering temperature may be less than or equal to 300° C.

The green body or work piece is sintered or bonded together at a temperature less than 1750° C. under vacuum by infiltrating wetting elements or wetting alloys into the green body or work piece. According to one alternative the sintering temperature may be less than 1700° C. The method according to the present invention also includes that the bonding or sintering is carried out by infiltration in an inert gas atmosphere at a pressure less than or equal to 200 Bar at a temperature less than 1700° C. According to another method, the infiltration may be carried out at a pressure less than or equal to 100 Bar. The inert atmosphere could be comprised of argon, nitrogen, hydrogen or mixtures thereof.

The infiltrating materials could be one or more wetting elements or one or more alloys of one or more wetting elements. It is important that the wetting angle of the wetting material on the work piece is <90°. According to another alternative, the wetting angle is small and could be ≦45°.

In the sintering step of the method of the invention the amount of wetting materials, which are used for infiltrating the work piece, may be at least 5 wt % more than the theoretical amount, which secures a complete infiltration of the work piece.

The infiltrating materials of the invention, could be wetting elements, which could be one or more elements selected from the group consisting of manganese (Mn), titanium (Ti), chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), aluminium (Al), and silicon (Si). According to one alternative the wetting elements may be selected from one or more elements of the group consisting of Ti, Mn, Cr, Cu and Si.

According to one alternative of the invention, the infiltrating materials may be wetting alloys. The wetting alloys could be alloys of two or more elements selected from the group consisting of manganese (Mn), titanium (Ti), chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), aluminium (Al), and silicon (Si). According to one alternative the wetting alloys may be selected from two or more elements of the group consisting of Ti, Mn, Cr, Cu and Si.

According to one alternative of the invention, the wetting elements or the wetting alloys have a liquidus temperature of less than or equal to 1500° C. According to another alternative the wetting elements or the wetting alloys may have a liquidus temperature of less than or equal to 1450° C. According to another alternative the wetting elements or the wetting alloys may have a liquidus temperature of less than or equal to 1400° C.

The present invention relates further to a green body, which comprises diamonds and filler material. Optionally the green body may contain a binding material. The filler materials being one or more elements or one or more alloys of the elements from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), technetium (Tc), rhenium (Re), iron (Fe), cobalt (Co), nickel (Ni), and silicon (Si). According to one alternative the filler materials may be selected from one or more elements or alloys of one or more elements of the group consisting of Ti, Cr, Mo, W and Co.

The green body according to the invention can have an amount of metal filler particles (Me) in an amount less than 100 percent by weight (wt %) and the amount of diamond particles is (D) in an amount D=100 wt %−Me. According to one alternative of the invention the amount of filler particles may be within the range 0.1 to 55 wt % and the amount of diamond particles is within the range 45 to 99.9 wt %. According to another alternative the amount of filler particles may be within the range 0.5 to 50 wt % and the amount of diamond particles is within the range 50 to 99.5 wt %. According to a further alternative the amount of filler particles may be within the range 1.0 to 45 wt % and the amount of diamond particles is within the range 55 to 99 wt %. Optionally the mixture of metal filler particles and diamond particles also may comprise a binding material. The binder could be any binder known in the art including but not limited to polymers, resin, cellulose, starch, and the like. The amount of binder is ≦50% by volume for a porosity of ≦50 vol %, or the amount of binder should be as small as possible. The amount of binder may be ≦10 percent by weight (wt %).

The present invention relates further to a diamond composite, which includes diamonds, filler material and wetting materials, and/or reaction products between diamond, metal filler and wetting elements. The filler materials being one or more elements or one or more alloys of the elements from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), technetium (Tc), rhenium (Re), iron (Fe), cobalt (Co), nickel (Ni), and silicon (Si). According to one alternative the filler materials may be selected from one or more elements or alloys of one or more elements of the group consisting of Ti, Cr, Mo, W and Co. The wetting materials being one or more elements selected from the group consisting of manganese (Mn), titanium (Ti), chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), aluminium (Al), and silicon (Si). According to one alternative the wetting elements may be selected from one or more elements of the group consisting of Ti, Mn, Cr, Cu and Si.

According to one alternative of the invention the wetting materials may be wetting alloys. The wetting alloys could be alloys of two or more elements selected from the group consisting of manganese (Mn), titanium (Ti), chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), aluminium (Al), and silicon (Si). According to one alternative the wetting alloys may be selected from two or more elements of the group consisting of Ti, Mn, Cr, Cu and Si.

The present invention relates further to products obtained by the method of the invention. The present invention relates further to uses of the diamond composite as a hard and/or abrasive material. Yet another alternative of the present invention is the use of the diamond metal composite as a material in nozzles, sleeves, tiles, tubes or plates, cutting tools, drilling bits or mining inserts. Yet another alternative may the nozzles, sleeves, tiles, tubes or plates be used in places where there is wear. Yet another alternative may the nozzles be used in high-speed centrifuges.

Further embodiments of the invention are defined in the claims. The invention is explained in more detail in by means the following Examples. The purpose of the Examples is to test the diamond composite of the invention, and is not intended to limit the scope of invention.

Example 1: Preparation of Diamond/Chromium Composites

To illustrate that a wide content of metal filler can be introduced into the diamond-metal composite material, a series of diamond/chromium composites were prepared. Diamond powder with a particle size range 5-30 μm was mixed with Cr powder in different weight ratio. Resin used as pressing binder, and details are listed in Table 1. The powder mixtures were stirred in an ethanol solution, and then dried in the air.

Discs with 18 mm diameter and 2-3 mm thickness were formed by die pressing, with a pressing force of 65 kN for 10 sec. The green bodies were slowly heated up to 160° C. for 1 hour. Sintering was performed in vacuum by Si infiltration at 1565° C. for 6 min. The densities of different samples are given in Table 1.

TABLE 1 Cr (wt. %) 2 8 15 20 25 45 Binder (wt. %) 5 4.5 4 3.7 3.4 3.2 Density (g/cm³) 3.34 3.36 3.36 3.41 3.44 3.67

Table 1 shows that with increasing amounts of Cr-filler the density of the composite is also increasing. It can be expected the thermal expansion, fracture toughness and brazing ability will be also increased. This shows the possibility to design the composite to a desired application.

Example 2: Preparation of Metal/Diamond Composites

W and Mo were mixed with diamond powder (particle size 5-10 μm), respectively. The metal/diamond weight ratio was 90:10. Forming of discs were heat-treated the same way as in Example 1. Sintering was performed in a graphite furnace. The samples were heated at 470° C. for 10 min., and then 700° C. for 30 min. in a N₂+4% H₂ atmosphere. The infiltration with Cu was carried out in vacuum at 1280° C. for 30 min. The density of W/diamond and Mo/diamond were 9.27 and 7.85 g/cm³, respectively. The results show that the selected metal filler element also has an influence on the property, such as the density.

Example 3: Preparation of Diamond/Metal Composites

Six different diamond/metal composites were prepared by similar way as in Example 1. The diamond/metal weight ratio was 92:8. The densities of different samples is given in Table 2.

TABLE 2 Metal Ti Cr Mo W Co Cr + Mo Metal (wt. %) 8 8 8 8 8 4 + 4 Density (g/cm³) 3.27 3.36 3.43 3.46 3.32 3.40

The results in Table 2 show that with the same amount of metal filler it will give different density of the composites, which depends on the type of the metal filler or the combination of the metal fillers.

While the present disclosure has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

What is claimed is:
 1. A diamond metal composite body obtained by mixing diamond particles with metal-filler particles forming a diamond/metal-filler mixture, forming a green body of the diamond/metal-filler mixture, optionally green machining the green body to a work piece before or after pre-sintering by heating the green body to a temperature <500° C., infiltrating the green body or the work piece with one or more wetting elements or infiltrating the green body or the work piece with one or more wetting alloys, the infiltration step being carried out under vacuum or in an inert gas atmosphere at a pressure <200 Bar, wherein the diamond metal composite body comprises diamonds, filler particles and wetting elements or wetting alloys, wherein the filler particles are selected from one or more elements or one or more alloys of the elements from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Tc, Re, Fe, Co, Ni, and Si, and wherein the wetting elements or the wetting alloys being selected from one or more elements of the group consisting of Mn, Cr, Mo, W, Fe, Co, Ni, Cu, Ag, Au, Al, and Si.
 2. A diamond metal composite body comprising diamond particles, metal filler particles, one or more wetting elements or one or more wetting alloys, and reaction products between diamond, metal filler and wetting elements, obtained by mixing the diamond particles with the metal-filler particles forming a diamond/metal-filler mixture, forming a green body of the diamond/metal-filler mixture and machining the green body before or after pre-sintering, wherein the green machining being cutting, sawing, drilling, milling, or turning, pre-sintering by heating the green body to a temperature <500° C., infiltrating the green body or the work piece with one or more wetting elements or infiltrating the green body or the work piece with one or more wetting alloys, which infiltration step being carried out under vacuum or in an inert gas atmosphere at a pressure <200 Bar.
 3. The diamond metal composite body according to claim 2, wherein the green body comprises a binder selected from the group consisting of polymers, resin, cellulose and starch, and the amount of the binder being less or equal to 10 wt %. 